Polymeric molds are typically made from silicone rubbers and urethane rubbers. Silicone rubbers often have high oxygen solubility which can undesirably lead to inhibition of free radical curing reactions used to make molded articles from the silicone rubber molds. If a molded article is prepared by curing a silicone material in a silicone rubber mold, the adhesion between the two silicones may cause difficulty in releasing the molded article. Additionally, curing of silicone materials typically requires hours, so making multiple polymeric molds from a single master tool can be very time consuming. A particular disadvantage of urethane-based molds is often relatively difficult release of the molded article, particularly when no release agent is used.
Microstructured molds comprising features of less than several millimeters are used in replication processes for forming microstructured molded articles able to perform a specific function. The microstructured molded articles can be made directly from the microstructured mold which in turn is formed from a microstructured tool. Microstructured molded articles are used in a variety of applications including optical applications in which they function as prisms, lenses, light guides, and the like. In such applications, it is often critical that these microstructured molds be free of imperfections that might otherwise produce undesirable optical artifacts.